Yes, backing up all my HD (then initialize and create suitable partitions) would be a solution. The only back-up I can do is by writing 6 or 7 CD. What worry me is that while doing that I could face an immediate problem: First, will the invisible files be 'lost' in the process? I mean, registration numbers and so on that are loose in the system? In the other hand, if these files will be kept, I am going to face again the problem to have the Beta files I don't want and risk to overwrite part of the OSX 1.0...
Another way will be to create partitions using FWB disk tools V4.0, which I have but I haven't used before. The reason: I am reluctant to do so because: 1) I don't understant very well how to do it without to re-initialize first. I understand you can create anew partition with the free space available but the manual is not crystal-clear (e.g. what is the difference between 'unused' and 'unallocated' space), and I have just 1.2GB free. 2) FWB drivers have to be installed and I don't know if they can cause incompatibility with the new OSX enviroment